It was also mentioned that the monitor/tv could draw significant current from the hdmi 5v output pin, and the usb port of a laptop might start limiting the current for the entire board, which could lead to all kinds of issues.

So it's worth trying to power the board from a charger, and not from usb port of a PC.Note that the hdmi sketch waits for the terminal to be connected, so either remove the line waiting the serial port, or enter the bootloader with quick double tap on the button. It should output arduino logo on the hdmi.

I manage to get some image with green square in the top right corner multiple timeswhile running communication through HDMI developer board. Still never have I managed to get self-written sketches or test images onto the screen. Display I am using is acer g246hl.

I had a similar issue and went through 3 different monitors before I found one that works. I'm using an older HP Monitor going HDMI from the board to DVI on the monitor. This seemed to work. I tried with another with HDMI to RGB using a powered adapter and that did not work either.

I noticed on the monitor that is working it shows when switching between inputs that it recommends setting to 1680x1050 rather than the 640x480 the example is setting it to. Maybe adjusting the resolution in Vidor_GFX.h might help:Ex: #define VIDOR_WIDTH 1680 #define VIDOR_HEIGHT 1050

Although, I did try this but it did not change the resolution so I might be missing something.